Strength training can specifically refer to lifting very heavy loads slowly, as in powerlifting.

“Strength training often is used synonymously with resistance training but also it can be thought of specific to, let's say, power lifting where you're moving very heavy loads and necessarily, when you're lifting heavy loads, you're moving them very slowly, you can't...if I give you a very heavy load to lift, you can't move that fast or you'd be able to do more than whatever you're doing, you'd be able to do more repetitions than what you're doing.”